Generally, a mobile communication system is developed for the purpose of providing communication by securing the mobility of a user. With the support from the dramatic development of technologies, the mobile communication system has reached a level of providing a high-speed data communication service as well as voice communication. Recently, the standardization of a long term evolution (LTE)/LTE-advanced (LTE-A) system in 3rd generation partnership project (3GPP) is in the process, which is one of the next generation mobile communication systems. LTE is a technology of implementing high speed packet based communication with a transmission rate of up to about 100 Mbps. As the types of services using a wireless mobile communication system have been diversified, there has been a desire for a new technology for efficiently supporting newly introduced services. Accordingly, new methods and technologies for improving the quality of communication based on an LTE/LTE-A system have been studied.